'Twas brillig, and Marti Raudsepp at 25/04/10 21:37 did gyre and gimble: > When I adjust the volume in PulseAudio, I noticed that the volume for > my left speaker is being reduced more than the volume of my right > speaker. The difference is small, but annoying enough when using > headphones. > > So I set out to investigate with alsamixer and found that PA always > prefers scaling the "Front" volume control. When I set this control to > 100%, everything sounds fine, but reducing it does indeed introduce > the difference I mentioned above, even if the volumes are linked in > alsamixer. > > Other volume controls such as "Master Front", "PCM" etc seem to be unaffected. > > So as a workaround, I start up mplayer, pause it and set it to 100% > volume in PA, which forces software gain control. > > I don't think this is an ALSA problem? ALSA just simply interfaces all > those volume controls to the user and can't help if some of them are > broken. > > Since PulseAudio takes control of setting the levels, I think it's > also PA's responsibilty to also know about such hardware quirks? Nah, it's alsa's jobs to implement quirks. No point fixing it in all applications using alsa directly (while a rather advanced one, PA is just an alsa client too), better to fix it where the problem lies. > I assume that I'm not the first person to find a problem with a hw > mixer control, but I couldn't find any such "quirk databases" in > PulseAudio source tree. You can create a custom mixer path that avoids using "Front" but really this should work correctly in the first place. Look in /usr/share/pulseaudio/alsa-mixer/ In your case somethign like: sed -i 's/\[Element Front\]/\[Element Master Front\]/g' /usr/share/pulseaudio/alsa-mixer/paths/* would likely fix the problem (e.g. stop it playing with "Front" at all). But that is probably not the most elegant of solutions and like I say it's something that should really be solved in alsa to make the control work correctly. Col -- Colin Guthrie gmane(at)colin.guthr.ie http://colin.guthr.ie/ Day Job: Tribalogic Limited [http://www.tribalogic.net/] Open Source: Mandriva Linux Contributor [http://www.mandriva.com/] PulseAudio Hacker [http://www.pulseaudio.org/] Trac Hacker [http://trac.edgewall.org/]
